Electrolytic pickling apparatus



1, 1956 G. H. RENDEL ELECTROLYTIC PICKLlNG APPARATUS Filed July 8, 1955 F'll3 2- IN VE IV T 0R. GEORGE H. RE/VDEL /-//s Attorney United States Patent fiFice 2,759,888 Patented Aug. 21, 1956 ELECTROLYTHI PICKLING APPARATUS George H. Reudel, Pittsburgh, Pa., assignor to United States Steel Corporation, a corporation New dersey Application July 8, 1953, Serial No. 366,662

4 Claims. (Cl. 204-211) This invention relates to electrolytic pickling apparatus and more particularly to such apparatus for pickling strip in which a strip passes in a plurality of passes through an electrolyte. In many instances the strip passes over an entry and exit conductor roll and intermediate conductor rolls. Experience has shown that all the conductor rolls, especially the exit rolls, have a very short service life because their surfaces become roughened after a very short time. For that reason, the conductor rolls are sometimes omitted. However, this prevents individual control of current density in the separate passes so that it is impossible to vary the polarity and current density in the various passes.

it is therefore an object of my invention to provide electrolytic pickling apparatus for strip in which individual control of current density and polarity in the various passes is possible without the use of intermediate conductor rolls.

This and other objects will be more apparent after referring to the following specification and attached drawings, in which:

Figure 1 is a schematic view of the electrolytic pickling apparatus of my invention; and

Figure 2 is a view similar to Figure 1 showing a second embodiment of my invention.

Referring more particularly to Figure 1 of the drawings, the reference numeral 2 indicates an entry conductor roll over which a steel strip S passes into a tank t. In the tank 4 the strip S passes around a rubber insulated sink roll 6 between electrodes 8 and 10. From the tank 4 the strip S passes over a rubber insulated roll 12 into a second pickling tank 14. The tank 14 contains a sink roll 16, similar to roll 6, and electrodes 18 and 20, similar to electrodes 8 and 10. Both of the tanks 4 and 14 contain an electrolyte (pickling acid). If desired, the electrolyte containing means may consist of a single tank rather than two tanks as shown. From the tank 14 the strip passes over a roll 22, similar to roll 12, and then into a rinse tank 24 which contains water and/or water sprays for removing or diluting the acid which is carried on the strip from the pickling tanks. In the tank 24 the strip passes around a sink roll 26 and then passes from the tank 24 over an exit conductor roll 28. Generators 30, 32, 34 and 36 are provided for the electrodes 8, 10, 18 and 20, respectively. A common connection 38 between the first terminals of the generators is connected to ground. The first terminal of generator is also connected to the entry conductor roll 2 and the first terminal of generator 36 is connected to the eXit conductor roll 28. The second terminal of gencrtaors 30, 32, 34 and 36 are connected by means of leads 40, 42, 44 and 46 to the electrodes 8, 10, 1.8 and 20, respectively. The generators 36, 32, 34 and 36 have control fields 30F, 32F, 34F and 36F, respectively. The voltage output from each generator may be regulated from full potential positive through zero to full potential negative by means of control rheostats 30R, 32R, 34R and 36R. The rheostats are connected to a power source 48.

The operation of the device is as follows.

The strip S passes through the acid electrolyte in the tanks 4 and 14 between the electrodes 8, 10, 18 and 20, then through the wash tank 24 where the acid is washed ofi Hence, the conductor rolls are located at positions where the strip surfaces are free of acid and are not subjected to attack by the pickling solution. Current is supplied to electrodes 8, 10, 18 and 20 by means of their respective generators 30, 32, 34 and 36. The amount and direction of the current flowing to the various electrodes and to the conductor rolls is varied by changing the position of the arm of the rheostats 30R, 32R, 34R and 36R. The distribution in the various circuits depends upon the resistances of the circuits and the direction and quantity of the current generated by the various generators. T he conductor rolls carry the current required to provide electrical current balance in the pickling system because under any condition of operation the algebraic sum of the currents passing through the conductor rolls is equal to the algebraic sum of the current flowing from the generators to the pickling electrodes. When the pickling currents in tanks 4 and 14 are exactly in balance no current flows through the conductor rolls. While the conditions of the various circuits may vary greatly depending upon the requirement for best pickling conditions, several specific conditions will be described.

it the generator 30 is conducting 5000 amperes and generators 32, 3 and are conducting Zero amperes, 5000 amperes will flow from generator 36 through wire 40 to electrode 8, through the electrolyte to strip S which transfers it to conductor roll 2, and then back to generator 30. There will be no current flowing to any of the other electrodes.

By means of rheostats 30R, 32R, 34R and 36R, the output of generators 30, 32, 34 and 36 may be regulated so that 6000 amperes are generated by each generator. With 6000 amperes flowing from generator 30 to electrode 8, 6000 amperes flowing from electrode 10 to generator 32, 6000 amperes flowing from electrodes 18 to generator 34 and 6000 amperes flowing from generator 36 to electrode 20, there will be 6000 amperes flowing in the line between generators 32 and 30 and 6000 am peres flowing in the line between genertaors 34 and 36. There will be no current flowing in the line between generators 32 and 34 nor any current flowing in the conductor rolls 2 and 28. in order that the operator may know the exact conditions it is preferred to provide center-zero ammeters 50, 52, 54 and 56, one in each of the connections 40, 42, 4'4 and 46. These ammeters indicate both the amount and direction of current flow in the circuit. it will be understood that means other than that shown may be used to control the direction and flow of the current generated by the generators 30, 32, 34 and 36.

The electrodes, instead of being arranged vertically in two tanks, may be arranged horizontally in a single tank as shown in Figure 2. In this embodiment the strip S passes over entry conductor roll 2 into a pickling tank which is provided with sink rolls 60 and 62, one at each end thereof. Electrodes 8', 10', 18' and 20' are arranged in tandem in the tank 58. An exit conductor roll 23' is provided at the exit end of the tank. Current is supplied to the electrodes 8', l0, l8 and 20' by means of generators 30', 32, 34 and 36, respectively. If desired a wash tank may be provided between the tank and conductor roll 28. The electrical connections and controls are otherwise the same as those of Figure 1 and the operation is also the same.

While four generators and four sets of electrodes are shown in each of the embodiments described above the invention is not limited to this particular number of generators and electrodes. in all instances at least two generators are required with the connection leading from one generator to the entry conductor roll and from the other generator to the exit conductor roll. More than four sets of electrodes may also be used.

While several embodimentsof my invention have been shown-and described it will be apparent that other adaptations and modifications may be made without depart ing from the scope of the following claims.

I-claim:

l. Electrolytic pickling apparatus for strip comprising means for containing an electrolyte, only two conductor rolls, one of said rolls being an entry conductor roll over which the strip passes before passing into said electrolyte, the other of said rolls being an exit conductor roll over which the strip passes after passing through said electrolyte, a plurality of electrodes arranged in tandem in said means along the path of travel of said strip, a plurality of generators, means for individually varying the quantity and direction of current generated by each generator, current leads connecting a first terminal of the first of said generators to the entry conductor roll, cur rent leads connecting the second terminal of the first of said generators to the first of said electrodes, current leads connecting a first terminal of the last of said generat'ors to the exit conductor roll, current leads connecting the second terminal of the last of said generators to the last of said electrodes, and a common connection between the first terminals of said generators.

2. Electrolytic pickling apparatus according to claim 1 in which means are provided between the electrolyte and the exit conductor roll for washing the electrolyte from the strip.

3. Electrolytic pickling apparatus for strip comprising means for containing an electrolyte, only two conductor rolls, one of said rolls 'being an entry conductor roll over which the strip passes before passing into said electrolyte, the other of said rolls being an exit conductor roll over which the strip passes after passing through said electrolyte, a plurality of electrodes arranged in tandem in said means along the path of travel of said strip, at least three generators, means for individually varying the quantity and direction of current generated by each generator, a common connection between the first terminals of said generators, current leads connecting the first terminal of the first of said generators to the entry conductor roll, current leads connecting the second terminal of the first of said generators to the first of said electrodes, current leads connecting the first terminal of the last of said generators to the exit conductor roll, current leads connecting the second terminal of the last of said generators to the last of said electrodes, and current leads connecting the second terminal of each intermediate generator to an intermedaite electrode.

4. Electrolytic pickling apparatus according to claim 3 in which means are provided between the electrolyte and the exit conductor roll for washing the electrolyte from the strip.

References Cited in the file of this patent UNITED STATES PATENTS 2,165,326 Yerger et a1 July 11, 1939 2,512,328 Hays June 20, 1950 2,556,017 Vonada June 5, 1951 FOREIGN PATENTS 60,198 Norway Dec. 19, 1938 

1. ELECTROLYTIC PICKLING APPARATUS FOR STRIP COMPRISING MEANS FOR CONTAINING AN ELECTROLYTE, ONLY TWO CONDUCTOR ROLLS, ONE OF SAID ROLLS BEING AN ENTRY CONDUCTOR ROLL OVER WHICH THE STRIP PASSES BEFORE PASSING INTO SAID ELECTROLYTE, THE OTHER OF SAID ROLLS BEING AN EXIT CONDUCTOR ROLL OVER WHICH THE STRIP PASSES AFTER PASSING THROUGH SAID ELECTROLYTE, A PLURALITY OF ELECTRODES ARRANGED IN TANDEM IN SAID MEANS ALONG THE PATH OF TRAVEL OF SAID STRIP, A PLURALITY OF GENERATORS, MEANS FOR INDIVIDUALLY VARYING THE QUANTITY AND DIRECTION OF CURRENT GENERATED BY EACH GENERATOR, CURRENT LEADS CONNECTING A FIRST TERMINAL OF THE FIRST OF SAID GENERATORS TO THE ENTRY CONDUCTOR ROLL, CURRENT LEADS CONNECTING THE SECOND TERMINAL OF THE FIRST OF SAID GENERATORS TO THE FIRST OF SAID ELECTRODES, CURRENT LEADS CONNECTING A FIRST TERMINAL OF THE LAST OF SAID GENERATORS TO THE EXIT CONDUCTOR ROLL, CURRENT LEADS CONNECTING THE SECOND TERMINAL OF THE LAST OF SAID GENERATORS TO THE LAST OF SAID ELECTRODES, AND A COMMON CONNECTION BETWEEN THE FIRST TERMINALS OF SAID GENERATORS. 